Semiconductor manufacturing apparatus control system

ABSTRACT

To reduce a stop time of transportation of wafers which occurs when one stepper handles many kinds of products, before exposure of semiconductor wafers of a first cassette port  7   a  is completed, a process recipe for semiconductor wafers of a second cassette port  7   b  is obtained from a host computer  2,  the progress of the exposure of the semiconductor wafers of the first cassette port  7   a  is detected via a sequencer  5,  it is determined, based on the obtained process recipe, whether or not the semiconductor wafers of the second cassette port  7   b  can be transported to an exposure stage following the last semiconductor wafer of the first cassette port  7   a , and a stepper  1  is caused to perform exposure in accordance with the determination result and the progress detection result.

TECHNICAL FIELD

[0001] The present invention relates to a control system for asemiconductor manufacturing apparatus that controls the semiconductormanufacturing apparatus, such as a stepper, that transfers a pattern ona reticle to a wafer based on information obtained from a host computer.

BACKGROUND ART

[0002] A conventionally known manufacturing line that performs aphotolithographic process on a semiconductor device, liquid crystaldisplay element or the like comprises, as shown in FIG. 6, a pluralityof steppers 1 and one host computer 2 for controlling the plurality ofsteppers 1, the steppers and the host computer being connected to eachother via a communication line 3.

[0003] In such a manufacturing line, each stepper 1 is adapted toperform an exposure process under the control of the host computer 2.First, an operator manipulates an online terminal for the host computerto obtain a process recipe from the host computer 2. Then, after areticle is set in a reticle library capable of housing a plurality ofreticles, according to the process recipe, the operator gives thestepper 1 an instruction to start the process via the terminal and thehost computer. Thereby, after automatic replacement of the reticle, thestepper 1 transports a plurality of wafers housed in a predeterminedcassette onto an exposure stage one by one, transfers a pattern formedon the reticle to the wafer, and places the wafer having the patterntransferred thereto into the cassette.

[0004] The conventional stepper 1 requires the operator to stoptransportation of the wafers and perform the terminal manipulation orthe like every time exposure of all the wafers processed according tothe same process recipe is finished.

[0005] Therefore, in the case where a large number of wafers are subjectto exposure in the same process recipe as in the case of producing thememory, which was a mainstream of the conventional semiconductormanufacturing industry, that is, in the case where limited kinds ofproducts are to be provided in large quantity, the stepper 1 can performexposure on wafers housed in different cassettes sequentially withoutstopping transportation of the wafers, and thus, the availability ishigh.

[0006] However, in recent years, products that can be mass-produced,such as memories, tend to decrease in price, and thus, attentions ofmany semiconductor manufacturers has been shifted to manufacture ofhigh-value-added custom products. Since the above-described conventionalstepper 1 requires manipulation by the operator for a following processevery time the process recipe is changed, a time of waiting for theoperator manipulation is required. Thus, the stepper 1 is stopped untilthe operator starts the manipulation for the following process, andthus, there is a possibility that the availability of the stepper 1 isreduced. In particular, in the case where the number of wafers that isprocessed according to the same process recipe is small (in the casewhere many kinds of products are to be provided in small quantity), suchas in the case of manufacture of a custom product, there is apossibility that the availability of the stepper 1 and thus thethroughput thereof are significantly reduced.

[0007] Thus, in recent years, there has been developed an arrangement inwhich a process recipe for a second group of wafers is loaded into thestepper 1 before exposure of a first group of wafers is completed. Forexample, a known stepper 1 of this type incorporates cassettes eachhousing wafers processed according to a same process recipe to beadapted for manufacture of many kinds of products in small quantity,obtains from the host computer 2 a process recipe for wafers housed inanother cassette before exposure of all the wafers housed in onecassette is completed, and after exposure of the wafers is completed,replaces the reticle with a new one according to the new process recipeand then, starts transportation of the wafers housed in said anothercassette.

[0008] However, according to the latter conventional technique, sincethe recipe for the following group of wafers is transmitted to thestepper 1 from the host computer during exposure of the wafers, even ifthe number of wafers processed according to a same process recipe issmall, the availability of the stepper 1 can be prevented from beingreduced. However, since transportation of wafers is stopped every timeexposure of all the wafers housed in one cassette is completed, forexample, even if the wafers processed according to the same processrecipe cannot be housed in one cassette and is separately housed in twoor three cassettes, transportation of the wafers is stopped every timeexposure of the wafers in one cassette is completed. Thus, there is aproblem in that the availability of the stepper 1 and thus thethroughput thereof is low.

[0009] Such problems are not specific to the stepper 1 that performsexposure, and are also found in semiconductor manufacturing apparatusthat performs other processes.

[0010] The present invention has been devised to solve the problemsdescribed above found in the prior art. An object of the invention is toprovide a control system for a semiconductor manufacturing apparatusthat allows reduction of a stop time of transportation of wafers whichoccurs when one semiconductor manufacturing apparatus manufactures manykinds of products.

DISCLOSURE OF THE INVENTION

[0011] In order to attain the object described above, the presentinvention is provided as follows. That is, a control system for asemiconductor manufacturing apparatus according to the invention is acontrol system for a semiconductor manufacturing apparatus that controlsa semiconductor manufacturing apparatus that processes wafers housed ina cassette capable of housing a plurality of wafers based on informationobtained from a host computer, characterized in that the control systemcomprises: information obtaining means for obtaining information fromsaid host computer before processing of a first group of wafers housedin a predetermined cassette is completed, the information being to bereferenced when processing a second group of wafers, the second group ofwafers being housed in a cassette different from said predeterminedcassette and processed following said first group of wafers; progressdetecting means for detecting the progress of the processing of saidfirst group of wafers from said semiconductor manufacturing apparatus;and processing instructing means for determining, based on theinformation obtained by said information obtaining means, whether or notsaid second group of wafers can be transported to a process stagefollowing said first group of wafers and instructing said semiconductormanufacturing apparatus to perform the processing in accordance with thedetermination result and the detection result by said progress detectionmeans.

[0012] Thus, in the control system for a semiconductor manufacturingapparatus according to the invention, before processing of the firstgroup of wafers housed in the predetermined cassette is completed, theinformation which is to be referenced when processing the second groupof wafers housed in a cassette different from the predetermined cassetteand processed following the first group of wafers is first obtained fromsaid host computer, and the progress of the processing of the firstgroup of wafers is detected from the semiconductor manufacturingapparatus.

[0013] Then, based on the information obtained by said host computerobtaining means, it is determined whether or not said second group ofwafers can be transported to the process stage following said firstgroup of wafers. Then, in accordance with the determination result andthe progress information detected from the semiconductor manufacturingapparatus, the semiconductor manufacturing apparatus is caused toperform the processing. Therefore, for example, even when wafers to beprocessed according to a same process recipe cannot be accommodated inone cassette and are separately housed in two or three cassettes,transportation of the wafers can be prevented from being stopped eachtime processing for one cassette is completed. For example, whenprocessing of the second group of wafers is to be started, if it isdetermined that the processing need not be changed, the second waferscan be transported to the process stage following the last wafer of thefirst group of wafers housed in the first cassette. For example,compared with a method in which each time processing of all the wafershoused in a cassette is completed, a process recipe for wafers housed inanother cassette is obtained from the host computer 2, the time ofcommunication is eliminated, and the stop time of transportation ofwafers can be reduced. Thus, the availability and throughput of thesemiconductor manufacturing apparatus can be increased.

[0014] Furthermore, it maybe provided that when said processinginstructing means determines, based on the information obtained by saidinformation obtaining means, that said second group of wafers can betransported to the process stage following said first group of wafers,said processing instructing means instructs said semiconductormanufacturing apparatus to start transportation of said second group ofwafers immediately after said semiconductor manufacturing apparatustransports the last wafer of said first group of wafers housed in saidpredetermined cassette in accordance with the determination result andthe detection result by said progress detection means.

[0015] With such an arrangement, when it is determined that said secondgroup of wafers can be transported to the process stage following saidfirst group of wafers, said semiconductor manufacturing apparatus startstransportation of said second group of wafers immediately after saidsemiconductor manufacturing apparatus transports the last wafer of saidfirst group of wafers housed in said predetermined cassette. Therefore,the stop time of transportation of wafers can be eliminated, and theavailability and throughput of the semiconductor manufacturing apparatuscan be increased.

[0016] Besides, in order to attain the object described above, thecontrol system for a semiconductor manufacturing apparatus according tothe invention may be a control system for a semiconductor manufacturingapparatus that controls a semiconductor manufacturing apparatus based oninformation obtained from a host computer, characterized in that thecontrol system comprises: information obtaining means for obtaininginformation from said host computer before processing of a first groupof wafers is completed, the information being to be referenced whenprocessing a second group of wafers which is to be processed followingsaid first group of wafers; progress detecting means for detecting theprogress of the processing of said first group of wafers from saidsemiconductor manufacturing apparatus; and processing instructing meansfor determining, based on the information obtained by said informationobtaining means, whether or not said second group of wafers can betransported to a process stage following the last wafer of said firstgroup of wafers and instructing said semiconductor manufacturingapparatus to perform the processing in accordance with the determinationresult and the detection result by said progress detection means.

[0017] With such an arrangement, before processing of the first group ofwafers is completed, the information which is to be referenced whenprocessing the second group of wafers processed following the firstgroup of wafers is first obtained from said host computer, and theprogress of the processing of the first group of wafers is detected fromthe semiconductor manufacturing apparatus. Then, based on theinformation obtained by said host computer, it is determined whether ornot said second group of wafers can be transported to the process stagefollowing said first group of wafers. Then, in accordance with thedetermination result and the progress information detected from thesemiconductor manufacturing apparatus, the semiconductor manufacturingapparatus is caused to perform the processing. Therefore, for example,when processing of the second group of wafers is to be started, if it isdetermined that the processing need not be changed, the second group ofwafers can be transported to the process stage following the last waferof the first group of wafers. Thus, compared with a method in whichwhether the processing need be changed or not is determined after theprocessing of the first wafers is completed, the stop time oftransportation of wafers can be reduced, and the availability andthroughput of the semiconductor manufacturing apparatus can beincreased.

[0018] Furthermore, it may be provided that when said processinginstructing means determines, based on the information obtained by saidinformation obtaining means, that said second wafers can be transportedto the process stage following said first wafers, said processinginstructing means instructs said semiconductor manufacturing apparatusto start transportation of said second group of wafers immediately aftersaid semiconductor manufacturing apparatus transports the last wafer ofsaid first group of wafers in accordance with the determination resultand the detection result by said progress detection means.

[0019] With such an arrangement, when it is determined that said secondgroup of wafers can be transported to the process stage following saidfirst group of wafers, said semiconductor manufacturing apparatus startstransportation of said second group of wafers immediately after saidsemiconductor manufacturing apparatus transports the last wafer of saidfirst group of wafers. Therefore, the stop time of transportation ofwafers can be eliminated, and the availability and throughput of thesemiconductor manufacturing apparatus can be increased.

[0020] Furthermore it may be provided that said information obtainingmeans obtains new information from said host computer in accordance withthe information obtained by the information obtaining means and thedetection result by said progress detecting means.

[0021] Furthermore, the control system for a semiconductor manufacturingapparatus according to the invention is particularly effective incontrolling a stepper, which is a semiconductor manufacturing apparatus.That is, in order to attain the object described above, the controlsystem for a semiconductor manufacturing apparatus according to theinvention may be a control system for a semiconductor manufacturingapparatus that controls a stepper that performs exposure of wafershoused in a cassette capable of housing a plurality of wafers based oninformation obtained from a host computer, characterized in that thecontrol system comprises: information obtaining means for obtaininginformation from said host computer before exposure of a first group ofwafers housed in a predetermined cassette is completed, the informationbeing to be referenced when performing exposure of a second group ofwafers, the second group of wafers being housed in a cassette differentfrom said predetermined cassette and subject to exposure following saidfirst group of wafers; progress detecting means for detecting theprogress of the exposure of said first group of wafers from saidstepper; and exposure instructing means for determining, based on theinformation obtained by said information obtaining means, whether or notsaid second group of wafers can be transported to an exposure stagefollowing said first group of wafers and instructing said stepper toperform exposure in accordance with the determination result and thedetection result by said progress detection means.

[0022] With such an arrangement, before exposure of the first group ofwafers housed in the predetermined cassette is completed, theinformation which is to be referenced when performing exposure of thesecond group of wafers which is housed in a cassette different from thepredetermined cassette and subject to exposure following the first groupof wafers is first obtained from said host computer, and the progress ofthe exposure of the first group of wafers is detected from the stepper.

[0023] Then, based on the information obtained by said host computer, itis determined whether or not said second group of wafers can betransported to the exposure stage following said first group of wafers.Then, in accordance with the determination result and the progressinformation detected from the stepper, the stepper is caused to performexposure. Therefore, for example, even when wafers to be processedaccording to a same process recipe cannot be accommodated in onecassette and are separately housed in two or three cassettes,transportation of the wafers can be prevented from being stopped eachtime exposure for one cassette is completed. For example, when exposureof the second group of wafers is to be started, if it is determined thatthe reticle need not be replaced with a new one, the second wafers canbe transported to the exposure stage following the last wafer of thefirst group of wafers housed in the first cassette. For example,compared with a method in which each time exposure of all the wafershoused in a cassette is completed, a process recipe for wafers housed inanother cassette is obtained from the host computer 2, the time ofcommunication is eliminated, and the stop time of transportation ofwafers can be reduced. Thus, the availability and throughput of thestepper can be increased.

[0024] Furthermore, it may be provided that when said exposureinstructing means determines, based on the information obtained by saidinformation obtaining means, that said second group of wafers can betransported to the exposure stage following said first group of wafers,said exposure instructing means instructs said stepper to starttransportation of said second group of wafers immediately after saidstepper transports the last wafer of said first group of wafers housedin said predetermined cassette in accordance with the determinationresult and the detection result by said progress detection means.

[0025] With such an arrangement, when it is determined that said secondgroup of wafers can be transported to the exposure stage following saidfirst group of wafers, said stepper starts transportation of said secondgroup of wafers immediately after said stepper transports the last waferof said first group of wafers housed in said predetermined cassette.Therefore, the stop time of transportation of wafers can be eliminated,and the availability and throughput of the stepper can be increased.

[0026] Besides, in order to attain the object described above, thecontrol system for a semiconductor manufacturing apparatus according tothe invention may be a control system for a semiconductor manufacturingapparatus that controls a stepper based on information obtained from ahost computer, characterized in that the control system comprises:information obtaining means for obtaining information from said hostcomputer before exposure of a first group of wafers is completed, theinformation being to be referenced when performing exposure of a secondgroup of wafers which is to be subject to exposure following said firstgroup of wafers; progress detecting means for detecting the progress ofthe exposure of said first group of wafers from said stepper; andexposure instructing means for determining, based on the informationobtained by said information obtaining means, whether or not said secondgroup of wafers can be transported to an exposure stage following thelast wafer of said first group of wafers and instructing said stepper toperform exposure in accordance with the determination result and thedetection result by said progress detection means.

[0027] With such an arrangement, before exposure of the first group ofwafers is completed, the information which is to be referenced whenperforming exposure of the second group of wafers which is subject toexposure following the first group of wafers is first obtained from saidhost computer, and the progress of the exposure of the first group ofwafers is detected from the stepper. Then, based on the informationobtained by host computer, it is determined whether or not said secondgroup of wafers can be transported to the exposure stage following saidfirst group of wafers. Then, in accordance with the determination resultand the progress information detected from the stepper, the stepper iscaused to perform exposure. Therefore, for example, when exposure of thesecond group of wafers is to be started, if it is determined that thereticle need not be replaced with a new one, the second wafers can betransported to the exposure stage following the last wafer of the firstgroup of wafers. Thus, compared with a method in which whether thereticle need be replaced with a new one or not is determined after theexposure of the first wafers is completed, the stop time oftransportation of wafers can be reduced, and the availability andthroughput of the stepper can be increased.

[0028] Furthermore, it may be provided that when said exposureinstructing means determines, based on the information obtained by saidinformation obtaining means, that said second wafers can be transportedto the exposure stage following said first wafers, said exposureinstructing means instructs said stepper to start transportation of saidsecond group of wafers immediately after said stepper transports thelast wafer of said first group of wafers in accordance with thedetermination result and the detection result by said progress detectionmeans.

[0029] With such an arrangement, when it is determined that said secondgroup of wafers can be transported to the exposure stage following saidfirst group of wafers, said stepper starts transportation of said secondwafers immediately after said stepper transports the last wafer of saidfirst group of wafers. Therefore, the stop time of transportation ofwafers can be eliminated, and the availability and throughput of thestepper can be increased.

[0030] Furthermore, said information obtaining means may obtain newinformation from said host computer in accordance with the informationobtained by the information obtaining means and the detection result bysaid progress detecting means.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]FIG. 1 is a schematic diagram showing an arrangement of a steppercontrol system according to the invention;

[0032]FIG. 2 is a block diagram showing an arrangement of an onlinecontroller shown in FIG. 1;

[0033]FIG. 3 is a flow chart of a computation process executed by theonline controller shown in FIG. 1;

[0034]FIG. 4 illustrates comparison between a stepper operationaccording to prior art and a stepper operation according to the steppercontrol system of an embodiment;

[0035]FIG. 5 illustrates comparison between a throughput according toprior art and a throughput according to the stepper control system ofthe embodiment; and

[0036]FIG. 6 is a schematic diagram showing an arrangement of aconventional stepper control system.

BEST MODE FOR CARRYING OUT THE INVENTION

[0037] An embodiment of a stepper control system according to theinvention will be described below with reference to the drawings.

[0038]FIG. 1 is a schematic diagram showing an arrangement of thestepper control system according to the invention. As shown in FIG. 1,the stepper control system comprises one host computer 2 storingcorrespondences between lot numbers and process recipes and a pluralityof exposure stations 4 connected to the host computer 2 via acommunication line 3.

[0039] The exposure station 4 comprises a plurality of devices forobtaining a process recipe from the host computer 2 and sequentiallyperforms exposure. It comprises a stepper 1 for performing exposure of asemiconductor wafer, a sequencer 5 connected to the stepper 1 fordetecting the progress of the exposure from the stepper 1, and an onlinecontroller 6 connected to the host computer 2, the stepper 1 and thesequencer 5 for obtaining the process recipe from the host computer 2and the progress information about the exposure from the sequencer 5 andtransmitting a control signal generated based thereon to the stepper 1.

[0040] The stepper 1 comprises a first cassette port 7 a and a secondcassette port 7 b on each of which a wafer cassette for housingsemiconductor wafers can be mounted, a transfer unit 8 with an exposurestage for transferring a pattern on a reticle to the semiconductorwafers housed in the wafer cassettes on the first and second cassetteports 7 a and 7 b, a wafer transport unit (not shown) for transportingsemiconductor wafers between the first and second cassette ports 7 a, 7b and the transfer unit 8, and a console 9 for controlling the transferunit 8, the wafer transport unit and the like.

[0041] The sequencer 5 is connected to the first and second cassetteports 7 a, 7 b and the transfer unit 8 and obtains from the cassetteports 7 a, 7 b and the transfer unit 8, as progress information of theexposure, states of the first and second cassette ports 7 a and 7 b(during transportation, during process, process completion, waiting fortransportation) and a state of the transfer unit 8 (during process,waiting for process). The online controller 6 is connected to theconsole 9 and obtains from the console 9 various kinds of conditioninformation including reticle ID, amount of exposure, focus alignmentoffset.

[0042] Furthermore, each wafer cassette houses semiconductor wafersprocessed according to a same process recipe and has attached thereto abar code indicating a lot number associated with the process recipe. Thebar code on the wafer cassette mounted on the cassette port 7 a or 7 bis read by a bar code reader connected to the online controller 6.

[0043] The wafer transport unit removes a semiconductor wafer from thewafer cassette, transports the same to the transfer unit 8, receives thesemiconductor wafer having the pattern transferred thereto from thetransfer unit 8 and puts the same back into the wafer cassette.

[0044] The console 9 has a function of instructing turning on/off acarrier switch of the cassette port for starting wafer transportation inresponse to a process start signal transmitted from the onlinecontroller 6. If, during exposure of semiconductor wafers housed in thewafer cassette on one of the two cassette ports 7 a and 7 b, a carrierswitch associated with the other of the cassette ports 7 a and 7 b isturned on, immediately after the last semiconductor wafer is transportedfrom the wafer cassette on the one of the cassette ports 7 a and 7 b,the wafer transport unit starts transportation of the semiconductorwafers from the wafer cassette on the other of the cassette ports 7 aand 7 b, and exposure is performed on the semiconductor wafers in thewafer cassette according to the same process recipe.

[0045] If, during exposure of semiconductor wafers of the one of thecassette ports 7 a and 7 b, the online controller 6 receives a processrecipe different from that being executed from the host computer and theother of the cassette ports 7 a and 7 b has a wafer cassette mountedthereon, immediately after the pattern transfer to all the wafers in thewafer cassette on the one of the cassette ports 7 a and 7 b iscompleted, the received different process recipe is transferred from theonline controller to the console 9, and then, after replacement of thereticle or the like is completed, the process for the other of thecassette ports 7 a and 7 b is started.

[0046] In the case where, when any exposure has not been not performedafter the transfer unit 8 is powered on, a new process recipe isreceived from the online controller 6 and one of the cassette ports 7 aand 7 b has a wafer cassette mounted thereon, the transfer unit 8 startsreplacement of the reticle or the like according to the received newprocess recipe.

[0047]FIG. 2 is a block diagram showing an arrangement of the onlinecontroller 6 shown in FIG. 1. The online controller 6 comprises a CPU 10and a RAM 11 for storing a program or the like that is executed by theCPU 10, the CPU 10 and the RAM 11 being connected to each other via abus 12. To the CPU 10, a keyboard 14, a display 15, an external storagedevice 16, a bar code reader for the first and second cassette ports 7 aand 7 b, the console 9, the sequencer 5 and the host computer 2 areconnected via the bus 12 and an interface 13.

[0048] The CPU 10 executes the program stored in the RAM 11. Thereby,when exposure of the semiconductor wafers of one of the cassette ports 7a and 7 b is performed according to the detection result by thesequencer 5 and the information obtained from the console 9, the CPU 10transmits to the console 9 the process recipe for the semiconductorwafers of the other of the cassette ports 7 a and 7 b and a signal toturn on the carrier switch of the other of the cassette ports 7 a and 7b.

[0049] In the case where the first and second cassette ports 7 a and 7 bhas mounted thereon cassettes for which exposure is performed accordingto the same process recipe, when exposure of the semiconductor wafers ofone of the cassette ports 7 a and 7 b is being performed based on thedetection result by the sequencer 5 and the information obtained fromthe console 9, only the signal to turn on the carrier switch of theother of the cassette ports 7 a and 7 b is transmitted to the console 9.

[0050] The program described above is stored in the external storagedevice 16. The program is transferred to the RAM 11 when it is to beexecuted and executed by the CPU 10 with a predetermined control periodΔT (for example, 10 msec).

[0051] A computation process of the program is shown in a flow chart inFIG. 3. First, in step S100, a message to prompt the operator to mount anew wafer cassette on an available one of the first and second cassetteports 7 a and 7 b is shown on the display 15, and then the processcontinues to step S101.

[0052] In step S101, based on the detection result by the sequencer, itis determined whether or not a new wafer cassette is mounted on thecassette port 7 a or 7 b for which the message which prompts mounting ofthe wafer cassette is displayed in step S100. If the wafer cassette ismounted on the cassette port (Yes), the process continues to step S102.If the wafer cassette is not mounted thereon (No), the determination isperformed again.

[0053] In step S102, the bar code reader connected to the onlinecontroller reads the lot number from the bar code attached to the newwafer cassette, and then, the process continues to step S103.

[0054] In step S103, a process recipe associated with the lot numberread in step S102 is loaded from the host computer 2, and the processrecipe is displayed on the display 15. Then, the process continues tostep S104.

[0055] In step S104, a message is displayed on the display 15 whichprompts the operator to manipulate a predetermined key of the keyboard14 after performing a manipulation “MV IN”, which indicates thatexposure of the semiconductor wafers housed in the new wafer cassettecan be performed according to the process recipe displayed on thedisplay 15 in step S103. Then, the process continues to step S105.

[0056] In step S105, it is determined whether or not the predeterminedkey of the keyboard 14 which is prompted to be manipulated in step S104is manipulated. If the key is manipulated (Yes), the process continuesto step S106. If the key is not manipulated (No), the determination isrepeatedly performed.

[0057] In step S106, based on the detection result by the sequencer 5,it is determined whether the semiconductor wafers are being subject toexposure or not. If the semiconductor wafers are being subject toexposure (Yes), the process continues to step S109. If the semiconductorwafers are not being subject to exposure (No), the process continues tostep S107.

[0058] In step S107, the process recipe loaded in step S103 and areticle replacement signal are transmitted to the console 9. Then, theprocess continues to step S108.

[0059] In step S108, a signal to turn on the carrier switch associatedwith the cassette port 7 a or 7 b on which the wafer cassette is mountedby the operator in step S100 is transmitted to the console 9, and then,the computation process is ended.

[0060] On the other hand, in step S109, a process condition of theexposure being performed is obtained from the console 9, and it isdetermined whether or not the process condition is the same as theprocess recipe loaded in step S103. If the process condition is the sameas the recipe (Yes), the process continues to step S110. If the processcondition is not the same as the recipe (No), the process continues tostep S111.

[0061] In step S110, a signal to turn on the carrier switch associatedwith the cassette port 7 a or 7 b on which the wafer cassette is mountedby the operator in step S100 is transmitted to the console 9, and then,the process continues to step S114.

[0062] On the other hand, in step S111, based on the detection result bythe sequencer 5 and a process end signal from the console 9, it isdetermined whether the wafer processing of all the wafers in the wafercassette which houses the group of semiconductor wafers being subject toexposure is completed or not. If the processing is completed (Yes), theprocess continues to step S112. If the processing is not completed (No),the determination is repeatedly performed.

[0063] In step S112, the process recipe loaded in step S103 and thereticle replacement signal is transmitted to the console 9, and then,the process continues to step S113.

[0064] In step S113, a signal to turn on the carrier switch associatedwith the cassette port 7 a or 7 b on which the wafer cassette is mountedby the operator in step S100 is transmitted to the console 9, and then,the process continues to step S114.

[0065] In step S114, based on the detection result by the sequencer 5,it is determined whether or not the last semiconductor wafer having beensubjected to exposure is transported into the wafer cassette housing thegroup of semiconductor wafers being subject to exposure. If the lastsemiconductor wafer is transported into the wafer cassette (Yes), theprocess continues to step S115. If the last semiconductor wafer is nottransported into the wafer cassette (No), the determination is performedagain.

[0066] In step S115, the operator is requested to perform a manipulation“MV OUT” to reconfirm the process condition for all the semiconductorwafers having been subject to exposure and confirm the number of wafersprocessed, and then, a message is displayed on the display 15 whichprompts the operator to manipulate a predetermined key of the keyboard14. Then, the process continues to step S116.

[0067] In step S116, it is determined whether or not the predeterminedkey of the keyboard 14 which is prompted to be manipulated in step S115is manipulated. If the key is manipulated (Yes), the process continuesto step S117. If the key is not manipulated (No), the determination isperformed again.

[0068] In step S117, a message is displayed on the display 15 whichprompts the operator to remove the wafer cassette housing thesemiconductor wafers having been subject to exposure from the first orsecond cassette port 7 a or 7 b. Then, the process continues to stepS118.

[0069] In step S118, it is determined whether or not the wafer cassettethat is requested to be removed is removed from the first or secondcassette port 7 a or 7 b in step S117. If the wafer cassette is removed(Yes), the computation process is ended. If the wafer cassette is notremoved (No), the determination is performed again.

[0070] Now, with reference to a specific situation, an operation of thestepper control system of the invention which is used in a factory thatmanufactures many kinds of products in small quantity, for example,manufactures custom products will be described.

[0071] First, suppose an operator in the factory powers on the stepper1, the host computer 2 and the online controller 6, and then, after alapse of a predetermined control period ΔT, the program stored in apredetermined area in the RAM 11 is activated. Then, in step S100, amessage to prompt the operator to mount a new wafer cassette on anavailable one of the first and second cassette ports 7 a and 7 b isdisplayed on the display 15. However, since the new wafer cassette hasnot been mounted at the point in time when the message is displayed, thedetermination in step S101 results in “No”, and the determination instep S101 is repeatedly performed.

[0072] Suppose the operator sees the message on the display 15 andmounts a new wafer cassette on the first cassette port 7 a complyingwith the message. Then, the sequencer 5 detects the wafer cassettemounted on the first cassette port 7 a, and the determination in stepS101 results in “Yes”. In step S102, the bar code reader connected tothe online controller reads the lot number from the bar code attached tothe new wafer cassette. In step S103, a process recipe associated withthe lot number read in step S102 is loaded from the host computer 2 anddisplayed on the display 15. In step S104, a message to prompt theoperator to manipulate a predetermined key of the keyboard 14 afterperforming “MV IN” is displayed on the display 15. However, since thepredetermined key has not been manipulated at the point in time when themessage is displayed, the determination in step S105 result in “No”, andthe determination in step S105 is repeatedly performed.

[0073] Suppose the operator sees the message on the display 15 andmanipulates the predetermined key after performing “MV IN” complyingwith the message. Then, the determination in step S105 results in “Yes”.Besides, since the computation process is performed for the first timesince the online controller 6 has been powered on, the determination instep S106 results in “No”. In step S107, the process recipe loaded instep S103 and a reticle replacement signal is transmitted to the console9. Instep S108, a signal to turn on the carrier switch associated withthe first cassette port 7 a is transmitted to the console 9, and then,the computation process is ended.

[0074] The console 9 having received the new process recipe from theonline controller 6 and the signal to turn on the carrier switchassociated with the first cassette port 7 a makes the transfer unit 8replace the reticle according to the received process recipe and so onand then makes the wafer transport unit start transportation of thesemiconductor wafers from the wafer cassette on the first cassette port7 a.

[0075] Suppose the program stored in the predetermined area in the RAM11 is activated again after a lapse of the predetermined control periodΔT after the end of the preceding computation process. Then, in stepS100, a message to prompt the operator to mount a new wafer cassette onthe second cassette port 7 b is displayed on the display 15. However,since the new wafer cassette has not been mounted at the point in timewhen the message is displayed, the determination in step S101 results in“No”, and the determination in step S101 is repeatedly performed.

[0076] Suppose the operator sees the message on the display 15 andmounts a new wafer cassette on the second cassette port 7 b complyingwith the message. Then, the sequencer 5 detects the wafer cassettemounted on the second cassette port 7 b, and the determination in stepS101 results in “Yes”. In step S102, the bar code reader connected tothe online controller reads the lot number from the bar code attached tothe new wafer cassette. In step S103, a process recipe associated withthe lot number read in step S102 is loaded from the host computer 2 anddisplayed on the display 15. In step S104, a message to prompt theoperator to manipulate a predetermined key of the keyboard 14 afterperforming “MV IN” is displayed on the display 15. However, since thepredetermined key has not been manipulated at the point in time when themessage is displayed, the determination in step S105 result in “No”, andthe determination in step S105 is repeatedly performed.

[0077] Suppose the operator sees the message on the display 15 andmanipulates the predetermined key after performing “MV IN” complyingwith the message. Then, the determination in step S105 results in “Yes”.Besides, since the semiconductor wafers of the first cassette port 7 aare being subject to exposure, the determination in step S106 results in“Yes”.

[0078] Here, it is supposed that the process recipe loaded in step S103is different from that loaded in the preceding computation process.Then, the determination in step S109 results in “No”, the determinationin step S111 results in “No”, and the determination in step S111 isrepeatedly performed.

[0079] Suppose processing of all the wafers of the wafer cassettemounted on the first cassette port 7 a is completed when thedetermination in step S111 is being repeatedly performed. Then, thedetermination in step S111 results in “Yes”. In step S112, the processrecipe loaded in step S103 and the reticle replacement signal aretransmitted to the console 9. In step S113, the signal to turn on thecarrier switch associated with the second cassette port 7 b istransmitted to the console 9.

[0080] The console 9 having received the new process recipe and reticlereplacement signal from the online controller 6 and been instructed toturn on the carrier switch associated with the second cassette port 7 breceives the process recipe and reticle replacement signal for thesecond cassette port 7 b from the online controller and startsreplacement of the reticle according to the process recipe immediatelyafter pattern transfer for the wafer cassette on the first cassette port7 a is completed.

[0081] In this way, if it is determined that the reticle needs to bereplaced with a new one to start exposure of the semiconductor wafers ofthe second cassette port 7 b, replacement of the reticle is startedimmediately after the last semiconductor wafer is transported into thewafer cassette on the first cassette port 7 a. Therefore, unlike themethod of performing the MVIN manipulation for the following differentprocess recipe via an operator manipulation after transportation of thesemiconductor wafers is completed, there is no waiting time for theoperator manipulation, and thus, the availability and throughput of thestepper are increased.

[0082] Furthermore, suppose the semiconductor wafers processed accordingto a same process recipe cannot be accommodated in one wafer cassette,and the wafer cassette mounted on the second cassette port 7 b alsohouses the semiconductor wafers subjected to exposure according to thesame process recipe as that for the wafer cassette mounted on the firstcassette port 7 a. Then, the determination in step S109 results in“Yes”, and in step S110, the signal to turn on the carrier switchassociated with the second cassette port 7 b is transmitted to theconsole 9.

[0083] Then, when the carrier switch associated with the second cassetteport 7 b is turned on, the cassette port 7 b makes the wafer transportunit start transportation of the semiconductor wafers from the wafercassette on the second cassette port 7 b immediately after the lastsemiconductor wafer is transported from the wafer cassette on the firstcassette port 7 a.

[0084] In this way, when it is determined that the reticle does not needto be replaced with a new one to start exposure of the semiconductorwafers of the second cassette port 7 b, transportation of thesemiconductor wafers of the second cassette ports 7 b is startedimmediately after the semiconductor wafers of the first cassette port 7a are transported. Therefore, there is no stop time of transportation ofthe semiconductor wafers, and thus, the availability and throughput ofthe stepper are increased.

[0085] Besides, if the process proceeds to step S114 via step S110 orS113, the determination in step S114 results in “No”, and thedetermination is repeatedly performed.

[0086] Suppose the last semiconductor wafer is transported from thewafer cassette mounted on the first cassette port 7 a when thedetermination in step S114 is being repeatedly performed. Then, thedetermination in step S114 results in “Yes”. And in step S115, a messageto prompt the operator to manipulate a predetermined key of the keyboard14 after performing “MV OUT” is displayed on the display 15. However,since the predetermined key has not been manipulated at the point intime when the message is displayed, the determination in step S116result in “No”, and the determination in step S116 is repeatedlyperformed.

[0087] Suppose the operator sees the message on the display 15 andmanipulates the predetermined key after performing “MV OUT” complyingwith the message. Then, in step S117, a message to prompt the operatorto remove the wafer cassette housing the semiconductor wafers havingbeen subject to exposure from the first cassette port 7 a is displayedon the display 15. However, since the wafer cassette has not beenremoved at the point in time when the message is displayed, thedetermination in step S118 results in “Yes”, and the determination instep S118 is repeatedly performed.

[0088] If the operator having seen the message on the display 15 removesthe wafer cassette complying with the message, the determination in stepS118 results in “Yes”, and the computation process ends.

[0089] By repeating the flow described above, as shown in FIG. 4,compared with the conventional technique in which after exposure of thesemiconductor wafers of one of the cassette ports 7 a and 7 b iscompleted, exposure of the semiconductor wafers of the other of thecassette ports 7 a and 7 b is started, the availability of the stepperis increased, and the throughput thereof is also increased as shown inFIG. 5.

[0090] In this embodiment, the online controller 6 and step S103 areequivalent to information obtaining means, the sequencer 5 is equivalentto the progress detection means and the online controller 6 and stepsS109 to S115 are equivalent to exposure instructing means.

[0091] In addition, the embodiment described above is only an example ofthe stepper control system according to the invention, the arrangementof the system or the like are not limited thereto.

[0092] For example, in the embodiment described above, if the processrecipe transmitted from the host computer 2 is the same as the processcondition of the current exposure processing, immediately after the lastsemiconductor wafer is transported from the wafer cassette on the firstcassette port 7 a, the wafer transport unit starts transportation of thesemiconductor wafers from the wafer cassette on the second cassette port7 b. However, the timing of starting transportation of the semiconductorwafers from the second cassette port 7 b is not limited to thatimmediately after the last semiconductor wafer is transported from thewafer cassette on the first cassette port 7 a. It is essential only thatthe timing precedes the transportation of the last semiconductor waferhaving the pattern transferred thereto into the wafer cassette.

[0093] Furthermore, in the example described above, one wafer cassettehouses a plurality of semiconductor wafers processed according to a sameprocess recipe. However, one wafer cassette may house a plurality ofsemiconductor wafers processed according to different process recipes.In such a case, when each semiconductor wafer is transported from thewafer cassette, it maybe determined whether or not the process recipefor the wafer is the same as that for the preceding one.

[0094] Furthermore, in the example described above, there are providedtwo cassette ports 7 a and 7 b, and when the semiconductor wafers housedin the wafer cassette on one of the cassette ports 7 a and 7 b are beingsubject to exposure, the process recipe for the semiconductor wafers ofthe other of the cassette ports 7 a and 7 b is obtained. However, forexample, in the case where three or more cassette ports are provided,when the semiconductor wafers of one of the cassette ports being subjectto exposure, the process recipes for the semiconductor wafers of all theother cassette ports may be obtained.

[0095] In the case where all the process recipes are to be obtained, forexample, rather than in the order in which the wafer cassettes aremounted on the cassette ports, a semiconductor wafer for which theprocess recipe is less changed may be subject to exposure by priority.

[0096] Furthermore, in the example described above, the onlinecontroller 6 obtains the process state in the transfer unit 8 via theconsole 9. However, the online controller 6 may directly obtain theprocess state from the transfer unit 8. Alternatively, a microcomputerdedicated to obtain the process state is provided, and the onlinecontroller 6 may obtain the process state from the transfer unit 8 viathe microcomputer rather than via the console 9.

[0097] Furthermore, the microcomputer may have a function similar tothat of the online controller 6, or the console 9 may have a functionsimilar to that of the online controller 6. Alternatively, the hostcomputer 2 may have a function similar to that of the online controller6.

[0098] Furthermore, the console 9 may have the functions of the onlinecontroller 6 and host computer 2.

INDUSTRIAL APPLICABILITY

[0099] As described above, the control system for a semiconductormanufacturing apparatus according to the invention is adapted todetermine whether, following a first group of wafers housed in apredetermined cassette, a second group of wafers housed in a cassettedifferent from the predetermined cassette can be transported to aprocess stage or not based on information obtained from a host computer.Therefore, for example, when processing of the second group of wafers isto be started, if it is determined that the processing need not bechanged, the second wafers can be transported to the process stagefollowing the last one of the first wafers housed in the first cassette.Thus, the stop time of transportation of wafers can be reduced, and theavailability and throughput of the semiconductor manufacturing apparatuscan be increased.

1. A control system for a semiconductor manufacturing apparatus thatcontrols a semiconductor manufacturing apparatus that processes wafershoused in a cassette capable of housing a plurality of wafers based oninformation obtained from a host computer, characterized in that thecontrol system comprises: information obtaining means for obtaininginformation from said host computer before processing of a first groupof wafers housed in a predetermined cassette is completed, theinformation being to be referenced when processing a second group ofwafers, the second group of wafers being housed in a cassette differentfrom said predetermined cassette and processed following said firstgroup of wafers; progress detecting means for detecting the progress ofthe processing of said first group of wafers from said semiconductormanufacturing apparatus; and processing instructing means fordetermining, based on the information obtained by said informationobtaining means, whether or not said second group of wafers can betransported to a process stage following said first group of wafers andinstructing said semiconductor manufacturing apparatus to perform theprocessing in accordance with the determination result and the detectionresult by said progress detection means.
 2. The control system for asemiconductor manufacturing apparatus according to claim 1,characterized in that when said processing instructing means determines,based on the information obtained by said information obtaining means,that said second group of wafers can be transported to the process stagefollowing said first group of wafers, said processing instructing meansinstructs said semiconductor manufacturing apparatus to starttransportation of said second group of wafers immediately after saidsemiconductor manufacturing apparatus transports the last wafer of saidfirst group of wafers housed in said predetermined cassette inaccordance with the determination result and the detection result bysaid progress detection means.
 3. A control system for a semiconductormanufacturing apparatus that controls a semiconductor manufacturingapparatus based on information obtained from a host computer,characterized in that the control system comprises: informationobtaining means for obtaining information from said host computer beforeprocessing of a first group of wafers is completed, the informationbeing to be referenced when processing a second group of wafers which isto be processed following said first group of wafers; progress detectingmeans for detecting the progress of the processing of said first groupof wafers from said semiconductor manufacturing apparatus; andprocessing instructing means for determining, based on the informationobtained by said information obtaining means, whether or not said secondgroup of wafers can be transported to a process stage following the lastwafer of said first group of wafers and instructing said semiconductormanufacturing apparatus to perform the processing in accordance with thedetermination result and the detection result by said progress detectionmeans.
 4. The control system for a semiconductor manufacturing apparatusaccording to claim 3, characterized in that when said processinginstructing means determines, based on the information obtained by saidinformation obtaining means, that said second wafers can be transportedto the process stage following said first wafers, said processinginstructing means instructs said semiconductor manufacturing apparatusto start transportation of said second group of wafers immediately aftersaid semiconductor manufacturing apparatus transports the last wafer ofsaid first group of wafers in accordance with the determination resultand the detection result by said progress detection means.
 5. Thecontrol system for a semiconductor manufacturing apparatus according toany one of claims 1 to 4, characterized in that said informationobtaining means obtains new information from said host computer inaccordance with the information obtained by the information obtainingmeans and the detection result by said progress detecting means.
 6. Acontrol system for a semiconductor manufacturing apparatus that controlsa stepper that performs exposure of wafers housed in a cassette capableof housing a plurality of wafers based on information obtained from ahost computer, characterized in that the control system comprises:information obtaining means for obtaining information from said hostcomputer before exposure of a first group of wafers housed in apredetermined cassette is completed, the information being to bereferenced when performing exposure of a second group of wafers, thesecond group of wafers being housed in a cassette different from saidpredetermined cassette and subject to exposure following said firstgroup of wafers; progress detecting means for detecting the progress ofthe exposure of said first group of wafers from said stepper; andexposure instructing means for determining, based on the informationobtained by said information obtaining means, whether or not said secondgroup of wafers can be transported to an exposure stage following saidfirst group of wafers and instructing said stepper to perform exposurein accordance with the determination result and the detection result bysaid progress detection means.
 7. The control system for a semiconductormanufacturing apparatus according to claim 6, characterized in that whensaid exposure instructing means determines, based on the informationobtained by said information obtaining means, that said second group ofwafers can be transported to the exposure stage following said firstgroup of wafers, said exposure instructing means instructs said stepperto start transportation of said second group of wafers immediately aftersaid stepper transports the last wafer of said first group of wafershoused in said predetermined cassette in accordance with thedetermination result and the detection result by said progress detectionmeans.
 8. A control system for a semiconductor manufacturing apparatusthat controls a stepper based on information obtained from a hostcomputer, characterized in that the control system comprises:information obtaining means for obtaining information from said hostcomputer before exposure of a first group of wafers is completed, theinformation being to be referenced when performing exposure of a secondgroup of wafers which is to be subject to exposure following said firstgroup of wafers; progress detecting means for detecting the progress ofthe exposure of said first group of wafers from said stepper; andexposure instructing means for determining, based on the informationobtained by said information obtaining means, whether or not said secondgroup of wafers can be transported to an exposure stage following thelast wafer of said first group of wafers and instructing said stepper toperform exposure in accordance with the determination result and thedetection result by said progress detection means.
 9. The control systemfor a semiconductor manufacturing apparatus according to claim 8,characterized in that when said exposure instructing means determines,based on the information obtained by said information obtaining means,that said second wafers can be transported to the exposure stagefollowing said first wafers, said exposure instructing means instructssaid stepper to start transportation of said second group of wafersimmediately after said stepper transports the last wafer of said firstgroup of wafers in accordance with the determination result and thedetection result by said progress detection means.
 10. The controlsystem for a semiconductor manufacturing apparatus according to any oneof claims 6 to 9, characterized in that said information obtaining meansobtains new information from said host computer in accordance with theinformation obtained by the information obtaining means and thedetection result by said progress detecting means.